Section 325.51102. Definitions.

Rule 2.  As used in these rules:

(a)      "Ceiling" means the  employee's   exposure  which  shall  not   be exceeded during any part of the workday. If instantaneous monitoring is not feasible, then the ceiling  shall   be  assessed  as   a    15-minute, time-weighted   average exposure which shall not be exceeded during any part of the working day.

(b)     "Skin designation" means those substances  so   indicated    that    have toxic effects due to absorption through an employee's skin.

(c)         "Short-term exposure limit (STEL)" means the employee's 15-minute, time-weighted average exposure which shall not be exceeded at any time during a workday, unless another time limit is specified in  a parenthetical notation below the limit. If another time period is specified, then the time-weighted average exposure over that time limit shall   not  be exceeded   at  any time during the workday.

(d)        "Time-weighted  average  (TWA)"  means     the      employee's       average airborne exposure in any 8-hour workshift of a 40-hour  workweek that shall not be exceeded.

(e)      The terms "substance"  and  "air   contaminant"  are      equivalent      in meaning for purposes of these rules.

History: 1990 AACS; 2001 AACS.